US8002482B2 - Transparent screen, projection display device, and method of receiving control signal light - Google Patents
Transparent screen, projection display device, and method of receiving control signal light Download PDFInfo
- Publication number
- US8002482B2 US8002482B2 US12/419,422 US41942209A US8002482B2 US 8002482 B2 US8002482 B2 US 8002482B2 US 41942209 A US41942209 A US 41942209A US 8002482 B2 US8002482 B2 US 8002482B2
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- United States
- Prior art keywords
- light
- fresnel
- control signal
- transparent screen
- prisms
- Prior art date
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/54—Accessories
- G03B21/56—Projection screens
- G03B21/60—Projection screens characterised by the nature of the surface
Definitions
- the present invention relates to a transparent screen which receives image light projected onto a rear side thereof as viewed from a side thereof which faces a viewer so as to display an image, a projection display device which projects image light onto the rear side of the screen so as to display an image, and a method of condensing control signal light applied to the transparent screen from a remote controller onto a photo detector to receive the control signal light.
- a projection display device is an image display device which consists of a Fresnel lens screen, a diffusion sheet (a diffusion layer), and so on. Unlike a CRT (Cathode Ray Tube) and a PDP (Plasma Display Panel), this projection display device is of non-light-emitting type.
- the projection display device is provided with, as a projector, an illuminating optical system for guiding light applied from a light source in a predetermined direction, a light valve for applying the light guided by the illuminating optical system, and for adjusting the amount of the light according to an image signal so as to form an image, and a projection optical system for expanding and projecting the image formed by the light valve onto a screen.
- Projection display devices include a display device of rear projection type which projects image light onto a rear side of the screen thereof as viewed from a viewer and a display device of front projection type which projects image light onto a front side of the screen thereof as viewed from a viewer.
- a transparent screen for use in a display device of back projection type, among these projection display devices includes a Fresnel lens screen for bending image light expanded and projected by a projector toward the viewer, and an image display element for forming an image of the image light from the Fresnel lens screen and for providing an angle of divergence for the image light so as to expand the image light.
- the remote controller uses a light signal having a wavelength which falls within a wavelength band of infrared rays including visible light rays. Because the Fresnel lens screen of a projection display device has a function of bending image light expanded and projected from a light source toward the direction of the viewer, the Fresnel lens screen also has a function of condensing control signal light from a remote controller applied thereto from the direction of the viewer onto a projector inversely. In other words, by using the Fresnel lens as a condensing lens, the control signal light applied from the remote controller can be condensed onto a photo detector efficiently.
- a Fresnel lens screen functions as a condenser lens which condenses incident light onto the optical axis of an optical system
- the Fresnel lens screen can condense control signal light applied from a remote controller onto a photo detector efficiently.
- a problem with a case in which a Fresnel lens screen, which is an eccentric optical system, for use in thin-type projection display devices which have seen in recent years is used is that most of the Fresnel lens cannot guide control signal light applied from a remote controller to a photo detector, and therefore the control signal light applied from the remote controller cannot be condensed onto the photo detector efficiently.
- the present invention is made in order to solve the above-mentioned problem, and it is therefore an object of the present invention to provide a transparent screen, a projection display device, and a control signal light receiving method which can guide control signal light applied from a remote controller to a photo detector efficiently even when using a Fresnel lens screen which is an eccentric optical system.
- a transparent screen in which, on a non-light incidence surface portion of a Fresnel optical element to which any light ray applied from a light emitting body is not applied directly because blocked by a Fresnel prism placed frontwardly, a plurality of Fresnel prisms each of which is smaller than the above-mentioned Fresnel prism and has a shape approximately similar to that of the above-mentioned Fresnel prism are arranged in a sawtooth shape.
- the transparent screen is constructed in such a way that, on the non-light incidence surface portion of the Fresnel optical element to which any light ray applied from a light emitting body is not applied directly because blocked by a Fresnel prism placed frontwardly, the plurality of Fresnel prisms each of which is smaller than the above-mentioned Fresnel prism and has a shape approximately similar to that of the above-mentioned Fresnel prism are arranged in a sawtooth shape. Therefore, the present embodiment offers an advantage of being able to guide control signal light applied from a remote controller toward a photo detector efficiently even when using the Fresnel lens screen which is an eccentric optical system.
- FIG. 1 is a configuration diagram showing a projection display device in accordance with Embodiment 1 of the present invention
- FIG. 2 is a perspective view showing the projection display device in accordance with Embodiment 1 of the present invention.
- FIG. 3 is a perspective view showing the interior of the projection display device in accordance with Embodiment 1 of the present invention.
- FIG. 4 is an explanatory drawing showing a deflection of the optical path of image light PB and a deflection of the optical path of control signal light CB which are caused by a transparent screen 10 in accordance with Embodiment 1 of the present invention;
- FIG. 5 is an explanatory drawing showing deflections of the optical paths in a case in which no Fresnel prism 12 d is placed on a non-light incidence surface of a light entering surface side Fresnel lens 12 in the transparent screen 10 of FIG. 3 ;
- FIG. 6 is an explanatory drawing showing examples in which the light entering surface side Fresnel lens 12 are produced through cutting using different cutting bites 52 and 53 ;
- FIG. 7 is a configuration diagram showing another example of the projection display device in accordance with Embodiment 1 of the present invention.
- FIG. 1 is a configuration diagram showing a projection display device in accordance with Embodiment 1 of the present invention.
- FIG. 2 is a perspective view showing the projection display device in accordance with Embodiment 1 of the present invention
- FIG. 3 is a perspective view showing the interior of the projection display device in accordance with Embodiment 1 of the present invention.
- a projector 1 is a light emitting body which is installed in a housing 7 of the projection display device, and which emits a light ray which is image light PB.
- the projector 1 is comprised of an illuminating optical system 2 , a light valve 3 , and a projection optical system 4 .
- the illuminating optical system 2 guides light applied thereto from a light source (not shown) in a predetermined direction.
- the light valve 3 applies the light guided by the illuminating optical system 2 to the projection optical system 4 , and carries out a process of adjusting the amount of the light according to an image signal to form an image.
- the projection optical system 4 expands and projects the image formed by the light valve 3 onto a transparent screen 10 .
- a remote controller 5 is remote operation equipment with which a user performs an operation of, for example, switching among images, and emits control signal light CB showing the operation.
- a photo detector 6 is equipment installed in the vicinity of the projector 1 for receiving the control signal light CB applied thereto from the remote controller 5 .
- the transparent screen 10 is comprised of a Fresnel lens screen 11 and an image display element 14 , and receives the image light PB applied thereto from the projector 1 and then emits the image light PB toward the viewer while receiving the control signal light CB applied thereto from the remote controller 5 and then emitting the control signal light CB toward the photo detector 6 .
- the Fresnel lens screen 11 is comprised of a light entering surface side Fresnel lens 12 and a base 13 , and has a function of bending the image light PB applied thereto from the projector 1 toward the direction of the viewer.
- the light entering surface side Fresnel lens 12 is a Fresnel optical element formed in the Fresnel lens screen 11 on a side of the light source (a light entering surface side) which is opposite to the viewer's side, in which a plurality of Fresnel prisms 12 a each of which has a refractive surface 12 b for refracting the image light PB applied thereto from the projector 1 and a reflecting surface 12 c for reflecting the image light PB refracted by the refractive surface 12 b are arranged in a sawtooth shape.
- a plurality of Fresnel prisms 12 d which are smaller than the Fresnel prisms 12 a and have a shape approximately similar to that of the Fresnel prisms 12 a are arranged in a sawtooth shape on each non-light incidence surface portion upon which the image light PB emitted from the projector 1 is not incident directly because the image light is blocked by a Fresnel prism placed frontwardly.
- the image display element 14 is comprised of a lens element 15 , a light diffusing member 16 , a base 17 , and a surface processing member 18 , and has a function of forming an image of the image light PB whose optical path has been bent by the Fresnel lens screen 11 , and also providing the image light PB with an angle of divergence so as to expand the image light PB.
- the lens element 15 has a function of providing the image light PB with an angle of divergence.
- the light diffusing member 16 has a function of forming an image of the image light PB.
- the base 17 holds the lens element 15 , the light diffusing member 16 , etc., and is formed of a resin such as PMMA (Poly Methyl Meth Acrylate), MS (Methyl methacylate Styrene), MBS (Methyl metacylate Butadiene Styrene), or PC (Polycarbonate).
- PMMA Poly Methyl Meth Acrylate
- MS Metal methacylate Styrene
- MBS Metal metacylate Butadiene Styrene
- PC Polycarbonate
- the surface processing member 18 can be comprised of various types of layers which are formed on a surface side of the image display element 14 which is the nearest to the viewer.
- the various types of layers can be an antireflection layer for reducing reflection of light in order to reduce the influence of ambient light, an anti glare layer for reducing visual glare, an antistatic layer for preventing adhesion of dust due to static electricity, and a hard coating layer for protecting the surface of the image display element 14 .
- the light diffusing member 16 is incorporated into the base in the form of layers so that a pair of light diffusing layers are formed, though, in a case in which the base 17 is made of glass, the light diffusing member 16 in the form of a film can be bonded to the base with a bonding layer.
- the light diffusing member 16 and the base 17 are arranged from the side of the light source to the side of the viewer in the order of the light diffusing member 16 and the base 17 , they can be inversely arranged in the order of the base 17 and the light diffusing member 16 .
- the base 17 can be integral with the light diffusing member 16 .
- O shows the optical axis of the optical system, and the optical system is arranged in an eccentric form in such a way that the optical axis O is aligned outside the transparent screen 10 which serves as the screen.
- the concentric circular Fresnel lens whose center is on the optical axis O is placed eccentrically in such a way that the optical axis O is shifted from the center O′ of the screen.
- the Fresnel lens screen 11 of the transparent screen 10 is a field lens which deflects the image light PB applied thereto from the projector 1 toward the direction of the viewer, and is designed so as to have the functions of a collimate lens for collimating the image light PB in such a way that the image light becomes substantially-collimated light.
- the light entering surface side Fresnel lens 12 of the Fresnel lens screen 11 has the functions of a condenser lens for condensing light applied thereto from the direction of the viewer toward the direction of the projection optical system 4 .
- control signal light CB applied from the remote controller 5 is incident upon the screen at an angle with the normal to the screen, and passes through the light diffusing member 16 , the lens element 15 , etc., it can be assumed that the light does not necessarily reach the projection optical system 4 and is received by the photo detector 6 located before the projection optical system 4 .
- FIG. 4 is an explanatory drawing showing a deflection of the optical path of the image light PB and deflections of the optical path of the control signal light CB in the transparent screen 10 in accordance with Embodiment 1 of the present invention.
- FIG. 5 is an explanatory drawing showing a deflection of the optical path of the image light PB and deflections of the optical path of the control signal light CB in a case in which no Fresnel prisms 12 d are arranged on each non-light incidence surface portion of the light entering surface side Fresnel lens 12 in the transparent screen 10 of FIG. 4 .
- the light entering surface side Fresnel lens 12 is constructed in such a way that the plurality of Fresnel prisms 12 a each of which has a refractive surface 12 b for refracting the image light PB applied thereto from the projector 1 and a reflecting surface 12 c for reflecting the image light PB refracted by the refractive surface 12 b toward the viewer are arranged in a sawtooth shape.
- the image light PB which is incident upon each Fresnel prism 12 a at an angle ⁇ in is emitted at an angle ⁇ ref1 by the refractive surface 12 b and the reflecting surface 12 c of each Fresnel prism 12 a.
- this relationship is shown by the following equation (1).
- ⁇ is the vertical angle of each Fresnel prism 12 a
- ⁇ is the angle of the refractive surface 12 b
- ⁇ is the angle (total reflection surface angle) of the reflecting surface 12 c.
- n 0 is the refractive index of the atmosphere
- n 1 is the refractive index of each Fresnel prism 12 a and the refractive index of the base 13 .
- the angle ⁇ is shown by the following equation (2).
- the total reflection surface angle ⁇ can be shown by the following equation (3).
- This equation (3) means that the total reflection surface angle ⁇ is a function of the incident angle ⁇ in , the function type being determined by two degrees of freedom: the total reflection surface angle ⁇ and the vertical angle ⁇ of each Fresnel prism 12 a. That is, because the viewer is placed in substantially front of the transparent screen 10 and the angle at which the image light is emitted from the screen is determined as ⁇ ref1 ⁇ 0, the total reflection surface angle ⁇ at the incident angle ⁇ in can be determined automatically when the vertical angle ⁇ of each Fresnel prism 12 a is determined.
- FIG. 5 shows the optical path of the image light PB applied from the projector 1 . Because the shape of the light entering surface side Fresnel lens 12 is determined in such a way as mentioned above, the image light PB applied from the projector 1 is bent toward the direction of the viewer.
- control signal light traveling along the optical path (each diagonally shaded portion) of the image light PB in the reverse direction i.e., the control signal light shown by a dotted line
- the control signal light which does not travel along the optical path (each diagonally shaded portion) of the image light PB in the reverse direction i.e., the control signal light shown by a dashed dotted line
- the condensing efficiency of the control signal light CB at that time approximately becomes equal to the percentage of each diagonally shaded portion, as shown in FIG. 5 , to the pitch m of the plurality of Fresnel prisms 12 a.
- the size of each diagonally shaded portion is about one-third of the pitch m of the plurality of Fresnel prisms 12 a
- about one-third of the control signal light CB can be condensed efficiently, but about two-thirds of the control signal light CB is lost.
- the percentage h of each diagonally shaded portion to the pitch m of the plurality of Fresnel prisms 12 a is shown by the following equation (5).
- a plurality of Fresnel prisms 12 d are arranged on each non-light incidence surface portion of the light entering surface side Fresnel lens 12 in the transparent screen 10 .
- each Fresnel prism 12 a which serve as the optical path (each diagonally shaded portion) of the image light PB are remained, and a plurality of Fresnel prisms 12 d which are a supplementary lens are arranged in each portion which does not serve as the optical path (each diagonally shaded portion) of the image light PB.
- the percentage l of the lens portion remained in the light entering surface side Fresnel lens 12 is calculated according to the following equation (6). It cannot be overemphasized that in actual, the percentage l can be set to a somewhat larger value by making the percentage have some margin (from 10% to 20%).
- each of the plural Fresnel prisms 12 d has only to have a shape substantially similar to that of each Fresnel prism 12 a which consists of the refractive surface 12 b and the reflecting surface 12 c in the easiest example.
- control signal light CB may propagate through a plurality of Fresnel prisms 12 a and may become stray light (refer to a dashed dotted line of FIG. 4 ), like in the case of the light entering surface side Fresnel lens 12 .
- each set of Fresnel prisms Fresnel prism 12 d which is a supplementary lens is configured in such a way that the control signal light CB applied from the remote controller 5 is emitted out while being shifted slightly (in the example of FIG. 4 , being shifted slightly upwardly) so that the control signal light CB is not blocked by each Fresnel prism 12 a placed frontwardly (refer to the dashed line of FIG. 4 ).
- each of the plurality of Fresnel prisms 12 d which are a supplementary lens is similar to that of each Fresnel prism 12 a
- what is necessary is just to slant each of the Fresnel prisms 12 d which are a supplementary lens.
- Each Fresnel prism 12 d arranged in a portion A 2 shown in FIG. 4 has a shape similar to that of each Fresnel prism 12 a, but its slanting surface is slightly slanted against a corresponding slanting surface of each Fresnel prism 12 a.
- each Fresnel prism 12 a and each Fresnel prism 12 d which is a supplementary lens are not necessarily similar to each other.
- the reason why each Fresnel prism 12 a and each Fresnel prism 12 d which is a supplementary lens are not necessarily similar to each other will be explained with reference to FIG. 6 .
- FIG. 6 is an explanatory drawing showing an example in which the light entering surface side Fresnel lens 12 is produced through cutting using different cutting bites 52 and 53 .
- the light entering surface side Fresnel lens 12 is produced by transferring the surface shape of a master mold 51 in which the shape of the Fresnel lens is carved onto a lens material.
- each supplementary lens portion is cut by using the cutting bite 52 and each Fresnel lens portion is cut by using the cutting bite 53 , and, as a result, each Fresnel prism 12 d which is a supplementary lens and each Fresnel prism 12 a can be formed in such a way that they do not necessarily have shapes similar to each other.
- each Fresnel prism 12 d which is a supplementary lens can be designed in such a way as to specialize in guiding the control signal light CB applied from the remote controller 5 toward a neighborhood of the projection optical system 4 , the control signal light CB can be condensed efficiently.
- Each set of a plurality of Fresnel prisms 12 d which are a supplementary lens is formed so as to guide the control signal light CB applied from the remote controller 5 to the photo detector 6 , and needs to be small compared with the pitch m of the plurality of Fresnel prisms 12 a in such a way as not to block the image light PB.
- the supplementary lens has a size which is of order of about several times to several ten times (a size of 5 microns) the wavelength of the control signal light, the image light is influenced not only by geometrical optics but by wave optics (for example, diffraction phenomena of light). Therefore, the pitch of the supplementary lens needs to be smaller than the pitch m of the plurality of the Fresnel prism 12 a, and needs to be larger than the wavelength lambda of the control signal light.
- the Fresnel lens screen 11 condenses light traveling in a direction normal to the screen efficiently, the Fresnel lens screen 11 can selectively condense only the control signal light CB applied from the remote controller 5 which is operated by the viewer who can be expected to stay in a direction substantially normal to the screen without condensing noise, such as light emitted from a fluorescent lamp.
- the projection display device in accordance with this Embodiment 1 is constructed in such a way that a plurality of Fresnel prisms 12 d each of which is smaller than each Fresnel prism 12 a and has a shape approximately similar to that of each Fresnel prism 12 a are arranged in a sawtooth shape on each non-light incidence surface portion, to which the image light PB applied from the projector 1 is not applied directly, of the light entering surface side Fresnel lens 12 because the image light PB is blocked by a Fresnel prism 12 a placed frontwardly. Therefore, the present embodiment offers an advantage of being able to guide the control signal light applied from the remote controller 5 toward the photo detector 6 efficiently even when using the Fresnel lens screen 11 which is an eccentric optical system.
- the Fresnel lens screen 11 receives the image light PB which is applied directly thereto from the projector 1 , as previously shown.
- at least one or more reflecting mirrors 19 are placed between the projector 1 and the Fresnel lens screen 11 in such a way that the Fresnel lens screen 11 receives the image light PB reflected by the one or more reflecting mirrors 19 .
- the projection display device can have, as its component, a holding mechanism, an air conditioner, a speaker, a television stand, an electrical circuit, a geometrical correction circuit, or a color correction circuit.
- the light emitting body which serves as the light source can be a lamp having a continuous spectrum, or a laser or LED (Light Emitting diode) having a discrete spectrum.
Abstract
Description
- [Patent reference 1] JP,63-2477,A (FIG. 2)
where τ is the vertical angle of each
[Equation 4]
ξ=π−τ−α (4)
Claims (9)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2008303685A JP5142963B2 (en) | 2008-11-28 | 2008-11-28 | Transmission screen, projection display device, and control signal light receiving method |
JP2008-303685 | 2008-11-28 |
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US20100134883A1 US20100134883A1 (en) | 2010-06-03 |
US8002482B2 true US8002482B2 (en) | 2011-08-23 |
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US12/419,422 Expired - Fee Related US8002482B2 (en) | 2008-11-28 | 2009-04-07 | Transparent screen, projection display device, and method of receiving control signal light |
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US (1) | US8002482B2 (en) |
JP (1) | JP5142963B2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11695904B2 (en) * | 2018-07-20 | 2023-07-04 | Dai Nippon Printing Co., Ltd. | Reflective screen and image display device |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2009075013A1 (en) * | 2007-12-10 | 2009-06-18 | Mitsubishi Electric Corporation | Transmission screen, projection display unit, and method for displaying image |
JP5388938B2 (en) | 2010-04-26 | 2014-01-15 | 三菱電機株式会社 | TRANSMISSION SCREEN, TRANSMISSION SCREEN IMAGE DISPLAY METHOD, AND PROJECTION DISPLAY DEVICE |
CN110908234B (en) * | 2018-08-28 | 2022-08-02 | 深圳光峰科技股份有限公司 | Curing adhesive and projection screen thereof |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS632477A (en) | 1986-06-20 | 1988-01-07 | Nec Home Electronics Ltd | Light receiving device for remote control in transmission screen type television receiver |
US4941036A (en) * | 1987-11-12 | 1990-07-10 | Mitsubishi Denki Kabushiki Kaisha | Command sensor in projection display apparatus |
US20070121208A1 (en) * | 2005-10-19 | 2007-05-31 | Sony Corporation | Transmissive screen and rear projection display apparatus |
US7242536B2 (en) * | 2003-12-17 | 2007-07-10 | Mitsubishi Denki Kabushiki Kaisha | Fresnel optical element and projection display device |
US20070285773A1 (en) * | 2006-04-13 | 2007-12-13 | Sony Corporation | Fresnel lens, prism array, rear projection display apparatus, and illuminating apparatus |
US20080180643A1 (en) * | 2007-01-25 | 2008-07-31 | Mitsubishi Electric Corporation | Projection display apparatus and method |
-
2008
- 2008-11-28 JP JP2008303685A patent/JP5142963B2/en not_active Expired - Fee Related
-
2009
- 2009-04-07 US US12/419,422 patent/US8002482B2/en not_active Expired - Fee Related
Patent Citations (6)
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JPS632477A (en) | 1986-06-20 | 1988-01-07 | Nec Home Electronics Ltd | Light receiving device for remote control in transmission screen type television receiver |
US4941036A (en) * | 1987-11-12 | 1990-07-10 | Mitsubishi Denki Kabushiki Kaisha | Command sensor in projection display apparatus |
US7242536B2 (en) * | 2003-12-17 | 2007-07-10 | Mitsubishi Denki Kabushiki Kaisha | Fresnel optical element and projection display device |
US20070121208A1 (en) * | 2005-10-19 | 2007-05-31 | Sony Corporation | Transmissive screen and rear projection display apparatus |
US20070285773A1 (en) * | 2006-04-13 | 2007-12-13 | Sony Corporation | Fresnel lens, prism array, rear projection display apparatus, and illuminating apparatus |
US20080180643A1 (en) * | 2007-01-25 | 2008-07-31 | Mitsubishi Electric Corporation | Projection display apparatus and method |
Non-Patent Citations (4)
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U.S. Appl. No. 12/359,652, filed Jan. 26, 2009, Endo, et al. |
U.S. Appl. No. 12/609,923, filed Oct. 30, 2009, Endo, et al. |
U.S. Appl. No. 14/747,420, filed Jun. 10, 2010, Endo, et al. |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11695904B2 (en) * | 2018-07-20 | 2023-07-04 | Dai Nippon Printing Co., Ltd. | Reflective screen and image display device |
Also Published As
Publication number | Publication date |
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JP5142963B2 (en) | 2013-02-13 |
JP2010128245A (en) | 2010-06-10 |
US20100134883A1 (en) | 2010-06-03 |
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